Conventionally, a heat exchanger that comprises a plurality of heat exchange units connected together in order to obtain a desired heat exchange capacity has been known as a cooling device installed, for example, in a vehicle. As a heat exchanger in which heat exchange units are disposed in a lateral direction, a radiator apparatus described in, for example, the Patent Document 1 has been proposed. On the other hand, as a heat exchanger in which heat exchange units are disposed in a vertical direction, a heat exchanger described in, for example, the Patent Document 2, has been proposed.
FIG. 7 depicts, as a first conventional example, the radiator apparatus described in the Patent Document 1. As shown in FIG. 7, each of heat exchange units 111 comprises: a pair of opposing tanks 115 and 116; tubes 113 by which the pair of tanks 115 and 116 communicate with each other; and fins 114 formed between the tubes 113.
The heat exchange units 111 are disposed in a lateral direction in the heat exchanger, the tanks 115, 115 are respectively connected each other, and the tanks 116, 116 are respectively connected each other by a pair of hoses 112.
FIG. 8 depicts, as a second conventional example, the heat exchanger described in the Patent Document 2. The heat exchanger shown in FIG. 8 is used for warming a room by causing hot water to flow within the heat exchanger. This heat exchanger comprises a plurality of heat exchange units 121 connected together. Each heat exchange unit 121 comprises: a hollow, polygonal tube 123 through which hot water flows; a series of plates 125 projecting from the polygonal tube 123; and parts forming the external contour of the series of plates 125. The heat exchanger is constructed by connecting and fixing together ends 122 of the adjacent polygonal tubes 123 using an adhesive.    Patent Document 1: Japanese Patent Laid-Open Publication No. 7-17449    Patent Document 2: Japanese Patent Laid-Open Publication No. 2000-161874